Key assemblies are known in the art. Key assemblies often comprise a keycap that works in combination with a contact-responsive switch. The keycap typically provides a surface configured to interact with an end-user's finger. By ordinarily biasing the keycap away from the contact-responsive switch, the end user can selectively press the keycap towards the contact-responsive switch to momentary close (or open, if desired) the latter. Upon releasing this pressure the keycap then returns to its stand-by position.
Some key assemblies are so-called film-style key assemblies. Such an assembly can comprise a silicone key mat having a raised area (presenting, for example, a relatively short isosceles-trapezoidal cross section) and a corresponding conformal upper layer comprised of a resilient material such as thermoplastic polyurethane (TPU). The key mat typically serves to make physical contact with the contact-responsive switch (or to at least transfer the end-user's finger pressure to that switch) while the resilient material typically serves to bias a corresponding keycap (which often has a flat, planar bottom surface that rests atop the aforementioned raised area) away from the contact-responsive switch.
While satisfactory for many application settings, such a film-style key assembly nevertheless poses certain concerns. For example, the keycap in such an assembly can sometimes be inadvertently peeled away from the raised area when subjected to a pulling force. As another example, such a key assembly can exhibit relatively poor tactile feel owing, at least in part, to having the resilient material conformally track the sides of the raised area of the silicone key mat. In particular, this configuration permits the resilient material to considerably increase the actuation force needed to urge the keycap towards the contact-responsive switch and hence increases the overall rigidity of the key assembly. This resilient material can also laterally transfer actuation forces in a manner that can permit unwanted interaction between, for example, adjacent key assemblies as comprise a part of a keyboard.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present disclosure. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present disclosure. Certain actions or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.